Increased telomerase activity and absence of p53 mutation in oligoastrocytomas induced by N-ethyl-N-nitrosourea in rats.

The question of whether the changes in telomerase activity and/or the alteration of the p53 gene are involved in the development of oligo-astrocytomas induced by N-ethyl-N-nitrosourea (ENU) in rats was addressed. Telomerase activity levels of oligo-astrocytomas, including early neoplastic lesions, were significantly increased as compared to the normal controls, correlating with the degree of malignancy. In contrast, no mutations of p53 exons 5-7 were found in early neoplastic lesions or oligo-astrocytomas. These results indicate that the activation of telomerase occurs during astrocytoma carcinogenesis and contributes to the development of brain tumors, but the alterations of p53, at least on exons 5-7, may not be involved in this process.